LISTENING EXPERIMENT

Each listener was presented with the notes , #, , and with or without vibrato followed by the same note without vibrato at 10 pitch levels in a randomized order. As mentioned earlier the mean of the vibrato note corresponds to the 0 level of the non vibrato note. There were eight repetitions of each comparison for a total of 640 trials for each person. The sound level was adjusted to a comfortable level by the subject. The stimuli were presented for approximately 1 s with an interstimulus interval of 250 ms. They were played through a Digidesign Audiomedia I board in mono using AKG k-240 monitor headphones. After hearing the two sounds, the subject clicked the appropriate box on the screen. Choices were definitely higher, maybe higher, maybe lower, or definitely lower. The subject could then click a box for the continuation of the experiment.